The article analyzes the bilateral structures asymmetry of bream Abramis brama (Linnaeus, 1758) populations in pilot reservoirs (lake Shitovskoye, pond Sylvinskiy) and populations of impact basin-coolers of the thermal power stations (lake-reservoir Isetskoye, reservoir Reftinskoye) in the Middle Urals, which was carried out using 27 non-metric skeleton features. The non-metric features analysis was implemented on 4 bream paired head bones. 10 dentale features, 4 operculum features, 7 praeoperculum features and 6 pteroticum features were studied. There has been calculated the dispersion of directional DA 2, fluctuating FA 2, total asymmetry TA 2 and the values of asymmetry indices FAnm . The fluctuating asymmetry FA 2 is found to contribute the most part (72-84 %) to the total asymmetry ТА 2 of bilateral features. The share of dispersion of directional asymmetry DA 2 in the dispersion of total asymmetry TA 2 is 16-28%. Intergroup differences between control and impact bream samples in the dispersion of directional asymmetry DA 2 was not significant ( p > 0.001). Significant increase in the dispersion of fluctuating asymmetry FA 2 and the values of individual asymmetry indicators FAnm have been identified in impact bream populations of thermal power station basin-coolers ( p < 0.001). The increased level of fluctuating asymmetry indirectly indicates destabilization of the bream morphogenesis in long-term habitat under thermal and chemical pollution. The results of the study can be used for organizing and conducting the environmental monitoring to assess the condition of bream populations in technologically disturbed reservoirs